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Article

Electrical Resistivity Control for Non-Volatile-Memory Electrodes Induced by Femtosecond Laser Irradiation of LaNiO3 Thin Films Produced by Pulsed Laser Deposition

by
Leonélio Cichetto Junior
1,*,
Carlos Doñate-Buendía
2,3,
María Teresa Flores-Arias
4,
Maria Aymerich
4,
João Paulo de Campos da Costa
5,
Eloísa Cordoncillo-Cordoncillo
6,
João Paulo Pereira do Carmo
5,
Oswaldo Hideo Ando Junior
7,
Héctor Beltrán Mir
6,
Juan Manuel Andrés Bort
8,
Elson Longo da Silva
9 and
Adenilson José Chiquito
1
1
Physical Department–NanOLaB, Federal University of São Carlos (UFSCar), São Carlos 13000-000, Brazil
2
GROC UJI, Institute of New Imaging Technologies, Universitat Jaume I (UJI), 12071 Castellón de la Plana, Spain
3
School of Mechanical Engineering and Safety Engineering, University of Wuppertal, 42119 Wuppertal, Germany
4
Department of Applied Physics, Institute of Materials (iMATUS), University of Santiago de Compostela (USC), E-15782 Santiago de Compostela, Spain
5
Department of Electrical Engineering (SEL), University of São Paulo (USP), São Carlos 13566-590, Brazil
6
Department of Inorganic and Organic Chemistry, Universitat Jaume I (UJI), 12071 Castellón de la Plana, Spain
7
Center for Alternative and Renewable Research (CEAR), Federal University of Paraiba (UFPB), João Pessoa 58051-900, Brazil
8
Department of Analytical and Physical Chemistry, Universitat Jaume I (UJI), 12071 Castellón de la Plana, Spain
9
CDMF, LIEC, Department of Chemistry, Federal University of São Carlos (UFSCar), São Carlos 13565-905, Brazil
*
Author to whom correspondence should be addressed.
Inorganics 2025, 13(9), 297; https://doi.org/10.3390/inorganics13090297
Submission received: 5 August 2025 / Revised: 22 August 2025 / Accepted: 29 August 2025 / Published: 2 September 2025
(This article belongs to the Special Issue Advanced Inorganic Semiconductor Materials, 3rd Edition)
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Versions Notes

Abstract

In this work, we investigated how the electrical resistivity of LaNiO3 thin films deposited on SrLaAlO4 (100), LaAlO3 (100), and MgO (100) single-crystal substrates by the pulsed laser deposition (PLD) technique can be controlled by femtosecond laser irradiation. Thin films were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (SEM-EDS), and temperature-dependent electrical resistivity measurements. The XRD data indicated good crystallinity and preferential crystallographic orientation. The electronic transport parameters of irradiated samples showed a remarkable decrease in the electrical resistivity for all studied films, which ranged from 38% to 52% depending on the temperature region considered and the type of substrate used. The results indicate a new and innovative route to decrease the electrical resistivity values in a precise, controlled, and localized manner, which could not be performed directly by well-known growth processes, allowing for direct application in non-volatile-memory electrodes.

1. Introduction

The compound LaNiO3 (LNO) is characterized by a perovskite structure with a pseudocubic lattice parameter (a = 0.384 nm). Bulk LNO exhibits Pauli paramagnetism [1] and Fermi-liquid behavior [2] at all temperatures. Band structures calculations for confined LNO films predict changes in electronic and magnetic properties [3], including the possibility of high-temperature superconductivity [4]. In recent years, LNO has drawn significant attention due to its use as a bottom electrode in non-volatile ferroelectric random-access memories (FeRAMs) and resistive random-access memories (ReRAMs), as well as fuel cells, microsensors, and capacitors [5,6,7,8,9,10,11,12].
Among these applications, LNO is particularly attractive as a bottom electrode in electronic devices. For this specific application, some distinct features are important, such as metallic behavior over a wide range of temperatures (1–1000 K), even when electrodes are only a few nanometers thick [13,14,15,16], and crack-free, oriented epitaxial growth [17,18] that improves electronic transport (e.g., carrier mobility) [13]. Moreover, when used as a bottom electrode in FeRAMs, LNO significantly mitigates ferroelectric fatigue [19].
For bottom electrodes, a key requirement is to minimize electrical resistivity across the operating temperature range. In the vast majority of studies carried out to reduce the electrical resistivity of LNO, many authors have investigated how the oxygen content can modify its electrical and structural properties [20]. In fact, the presence of oxygen vacancies can effectively control the resistivity of the material, i.e., LaNiO2.75 shows semiconducting behavior, while an insulating phase is obtained with a further decrease in oxygen content, as in LaNiO2.5 [21,22,23,24]. In addition, some authors have also investigated the performance of LNO films with different La/Ni ratios, as a function of the cation off-stoichiometry, and their effect on the (possible) reduction of electrical resistivity [25,26,27]. The electrical resistivity can be tuned according to the La/Ni ratio. For example, at La/Ni ≈ 0.83 and La/Ni ≈ 0.75 ratios, Zhu et al. [25] and Cole et al. [26] found a clear decrease in the electrical resistivity when compared to La/Ni = 1. From a structural point of view, when the La/Ni ratio is in the 0.75 < La/Ni < 0.85 range, the decrease in La content leads to a contraction in the c-axis (with respect to stoichiometric LNO) and, consequently, to increases in the Ni-O-Ni bond angle and the Ni-O bond length [26]. These early works indicate that the resistivity of LNO can change due to the local coordination of Ni cations (i.e., oxygen surroundings), leading to different hybridization strength effects between the Ni-3d t2g and O 2p states [28].
Variation in the Ni content, and consequently the La/Ni ratio, can be achieved in different ways, depending on the growth technique. In the pulsed laser deposition (PLD) technique [29], the La/Ni ratio is set by the target composition, which subsequently affects the thin-film stoichiometry. In molecular-beam epitaxy (MBE), the ratio is controlled by adjusting the elemental flux/source rates. When using the sol–gel method, La/Ni is defined by the molar ratio of the precursors [30]. In all these cases, the resulting films are typically highly stoichiometric and homogeneous, leading to uniform electrical properties. By design, these growth methods produce uniform stoichiometry and offer no practical handle to induce spatially resolved, thermally driven stoichiometric modifications.
To fulfill the modern industrial requirement of miniaturization, it is desirable to modify the electrical properties of local regions of LNO films with nano- to micrometric spatial resolution, to tune and control the local electrical resistivity. A direct application is the development of non-volatile-memory (NVM) technologies [31,32,33], which are fundamental for the next generation of electronic products.
To tailor material properties as outlined above, femtosecond laser irradiation has delivered remarkable results across diverse materials, proving a powerful route to induce modifications via light–matter interaction on ultrashort timescales [34,35,36,37]. These capabilities have been demonstrated across numerous materials and applications, such as surgery, microfabrication, annealing, and biomedical uses [38,39,40,41,42,43,44].
Laser technologies stand out for their versatility, accuracy, and precision. Owing to high-spatial-resolution femtosecond laser sources, micrometer-scale modifications can be performed in selected regions of films/substrates [45]. Another important feature is that femtosecond irradiation can induce microstructural modifications more efficiently by minimizing the damaged area around the ablated zone [46]. This is due to the short duration of the pulse in contrast to the electron-lattice relaxation time, resulting in an accurate interaction with a small or negligible heat-affected zone [47]. This is an advantage of using femtosecond in contrast to nanosecond pulsed lasers, where the thermally affected area is more significant in comparison to the ultra-short regime due to the mechanism involved in the process [48].
Based on these considerations, the report in this paper the growth of epitaxial LNO thin films on different single-crystal substrates by pulsed laser deposition (PLD), followed by localized femtosecond laser irradiation. The samples were characterized by XRD, SEM-EDS, and temperature-dependent electrical transport measurements. These techniques were applied to different selected areas of the films, some of which were non-irradiated, and others irradiated by a femtosecond laser beam. The results show a clear decrease in electrical resistivity in all irradiated regions, The results show a clear decrease in electrical resistivity in all irradiated regions, irrespective of the substrate. The temperature-dependent resistivity curves indicated that the electrical behavior of the samples remained unchanged. Therefore, the use of the route proposed in this work arises as an alternative that can be used to manipulate the electrical resistivity in a controlled and reliable way (in terms of dimension and intensity). In short, we present a fast procedure to tune the resistivity of PLD-grown LNO thin films by ultrashort femtosecond laser exposure, without any post-treatment.
In this context, the present work investigates the potential of femtosecond laser irradiation as a localized and efficient tool to modify the electrical resistivity of epitaxial LaNiO3 thin films grown by pulsed laser deposition on different single-crystal substrates. The films were selectively irradiated and analyzed to assess structural, morphological, and electrical changes resulting from the laser–material interaction. This paper is organized as follows: Section 2 details the experimental methods for film fabrication, laser irradiation, and characterization techniques. Section 3 presents and discusses the results, including the electrical, structural, and compositional changes induced by irradiation. Finally, Section 4 summarizes the key findings and their relevance for future applications in miniaturized electronic devices and non-volatile-memory technologies.

2. Results and Discussions

To avoid the influence of possible changes in film stoichiometry or thickness on the electrical measurements, electron-transport investigations were performed on films with only half of the surface area irradiated (Group I, as will be detailed in Section 3—Materials and Methods). Measuring the irradiated region and subsequently the non-irradiated region on the same film allowed for a direct comparison of changes induced by the laser–film interaction. Figure 1a shows a schematic of the electrical contacts used on the films. Measurements were taken for both increasing and decreasing temperatures on the irradiated and non-irradiated areas. The temperature-dependent resistivity curves are presented in Figure 1b,d. The ρ(T) curves show a clear decrease in the resistivity when comparing values before (green) and after (purple) irradiation, as summarized in Table 1. The resistivity of films grown on LAO and MgO substrates (see Figure 1b,c) shows a monotonic behavior as the temperature is lowered.
To complement these results, we aimed to understand how the laser scan used to irradiate the samples affects the type of electrical resistivity behavior in LNO films. Specifically, we investigated how the metal insulating transition (MIT) [49] presented in one of the films changes when irradiated by the femtosecond laser beam. Since MIT is closely tied to the structural changes of films, its evolution could be used as a probe of the femtosecond laser effect. The literature reports several approaches to understand the behavior of MIT in LNO films. Here, the curves presented in Figure 1d are not intended to establish a model, but rather to mark structural changes in our samples. The femtosecond laser irradiation resulted in a noticeable reduction in resistivity without changing the character of the mechanisms underlying the MIT effect, as can be seen in Figure 1d.
The resistivity was calculated from the measurement geometry using standard thin-film expressions, and the film thickness was determined from cross-sectional FEG-SEM. Another important factor verified during FEG-SEM characterization was a slight decrease in the film thickness due to the interaction with the femtosecond laser beam. On its own, such a contraction in the thickness would lead to an increase in the ρ(T) values, as shown in our previous work [13], which contrasts with the behavior found here (the resistivity of irradiated films also decreased). Thus, we believe that the lower ρ values after irradiation are related to the densification of the films, which in turn results in a different percolation path (showing lower resistance), for electrons.
Figure 1e,f shows a cross-sectional FEG-SEM image of an LNO/LAO film, highlighting the written (ablated) and non-written regions and the consequent narrowing of the irradiated area. SEM-EDS measurements indicate a stoichiometry change from La/Ni = 1 (non-irradiated region) to La/Ni ≈ 0.9 (irradiated region), which is consistent with the observed decrease in resistivity.
Figure 2a–c shows the XRD patterns of non-irradiated and irradiated LNO films grown on LAO, MgO, and SLAO substrates, respectively. The XRD patterns of all LNO films are in good agreement with the pseudo-cubic structure (space group Pm3m), according to the JCPDS 33-710 card. For the three different substrates, the LNO films exhibited only reflection peaks corresponding to the (100) orientation, indicating epitaxial growth on the oriented substrates. No impurities or secondary phases were detected in any of the samples. Due to the relatively low thickness of the LNO films, which affects the intensity of the reflection peaks compared to the respective substrates, a magnified view of the (200) peak region is shown as an inset in each XRD figure. Specifically in Figure 2c, the LNO (100) peak is also observed in the diffractogram of the non-irradiated region (blue). However, its intensity is lower, as the LNO (200) peaks were used as reference for the conclusions presented in Figure 2d,e.
In order to understand the effects of femtosecond laser irradiation on the crystal structure of LNO, an analysis of the interplanar distance of the most intense peak (200) was performed, and the lattice parameter was calculated for all samples, as shown in Figure 2d,e, respectively. We can see a difference in the d(200) values for the non-irradiated samples, which arises from the strain generated by the lattice mismatch in the specific substrate/film interface, that once the LNO tends to expand or contract, its unit cell tends to grow in the oriented direction of the substrate [50,51]. It was observed that the lattice parameter of the LNO films in the three substrates slightly decreases in the irradiated samples. However, due to the relatively low fluence of the femtosecond laser, the irradiation did not cause significant structural modifications or damage to the samples. These slight changes in the lattice parameter are directly related to changes in the coordination parameters of the composing clusters (building blocks), i.e., changes in the bond angles and lengths of the [NiO6] and [LaO12] [52,53]. Figure 2f shows the unit cell of the LNO structure with the visualization of the (100) plane. As can be seen, the atoms composing the interplanar distance of the (100) plane are the [NiO6] cluster. Herein, changes in the distance of this family of planes can be assigned to changes in the coordination parameters of [NiO6] clusters. Therefore, the slight compression of the d(200) and consequently of the lattice parameter due to the femtosecond laser irradiation can be related to distortions in the [NiO6] clusters. A decrease in the bond length and an increase in the bond angle of the [NiO6] is promoted to maintain its crystal structure, as predicted by the Jahn–Teller effect [54]. In brief, ultrashort pulses in ambient air drive a highly non-equilibrium, non-thermal interaction with a minimal heat-affected zone (HAZ). Under these conditions, preferential cation removal (surface La depletion) and slight oxygen redistribution can occur near the surface, resulting in La/Ni < 1 in the irradiated tracks, as measured by SEM-EDS (La/Ni ≈ 0.9). The resulting [NiO6] octahedral distortions (shorter Ni–O bonds, larger Ni–O–Ni angles) enhance bandwidth and reduce resistivity, consistent with prior reports that cation off-stoichiometry reduces ρ in LNO.
Regarding the reduction in electrical resistivity, we confirm that it is permanent when compared to the non-irradiated areas. Durability tests were conducted, and new electrical characterizations performed six months after the initial measurements showed that the resistivity reduction effects remained unchanged, both in magnitude and in the behavior of the ρ vs. T curves. This indicates that femtosecond laser irradiation is a reliable technique in terms of the durability of the resistivity reduction effect, i.e., it is not reversible. This is a key factor for potential applications in non-volatile-memory devices.

3. Materials and Methods

To evaluate the effects of femtosecond laser irradiation on the electrical resistivity of LaNiO3 thin films, a series of epitaxial films were fabricated and subjected to controlled post-deposition processing. The experimental procedures were designed to ensure reproducibility and enable direct comparison between irradiated and non-irradiated regions of the same sample. This section describes the fabrication of the LaNiO3 thin films using the pulsed laser deposition (PLD) technique, followed by the laser irradiation methodology, structural and morphological characterizations, and electrical transport measurements performed to analyze the impact of laser interaction on the physical properties of the films.

3.1. Manufacturing LaNiO3 Thin Films by PLD

LaNiO3 thin films were grown by pulsed laser deposition (PLD) on three single-crystal substrates: SrTiO3 (STO) (100), MgO (MgO) (100), and SrLaAlO4 (SLAO) (100). The LNO target was prepared by the Pechini method [55,56] to ensure compositional homogeneity during the ablation process. Before each deposition, the target surface was polished with SiC abrasive paper and conditioned with 1000 laser pulses using a laser fluence of 1.5 J/cm2 to stabilize the plume.
Substrates were preheated to 750 °C in the evacuated process chamber (≈10−7 mbar) and then cooled to the deposition temperature specified for each substrate (Table 2). After establishing a base oxygen pressure of 1.2 × 10−1 mbar, the film (thickness 90 nm, nominal growth rate 0.06 nm/s) was deposited using a pulsed laser beam. A focused Kr-F excimer laser (λ = 248 nm) was used, impinging the stoichiometric LNO target at 45° with a fluence of ~1.7 J/cm2, for all depositions, at a 4 Hz repetition rate. Table 2 summarizes the parameters used during the deposition of thin films by PLD for the different substrates.
The substrates were attached to the heater using colloidal silver paste, and the distance between the substrate and the target was set to 4 and 5 cm, depending on the substrate, as reported previously [13,56,57]. It is important to note that the film thickness depends not only on the number of laser pulses but also on the chamber pressure and the target–substrate spacing. Therefore, the number of pulses used for each film was chosen from prior growth-rate calibrations performed for each substrate. Post deposition in situ annealing was carried out at the sintering temperature for 1 h at 5 × 10−2 mbar to suppress oxygen vacancies and to preserve the phase stoichiometry of the film. After the oxygenation step, the samples were cooled to room temperature.

3.2. Femtosecond Laser Irradiation of LaNiO3 Thin Films

Samples were exposed to laser irradiation using the STELA laser (Santiago Terawatt Laser; model Alpha 10/XS, 45 TW; manufacturer: Thales Optronique SAS—Thales Laser Solutions, Élancourt, France) of the University of Santiago de Compostela (Spain), a Ti: Sapphire laser. The pulse duration was 35 fs at 800 nm central wavelength with a bandwidth of 75 nm. The maximum output energy was 1 mJ per pulse with a 1 kHz repetition rate.
The beam was focused onto the thin film with a high-precision XYZ stage (Lasing S. L) and kept normal to the surface of the thin films. A Mitutoyo M Plan APO NIR20X microscope objective was employed for this purpose, with an effective focal length of 10 mm. All irradiation processes were carried out in an air environment.
Tests were conducted to find the optimum parameters for the irradiation of the samples. First, keeping the laser power constant, lines with a length of 500 μm were drawn. The separation between the surface of the sample and the objective (see Figure 3a) was varied for each. In particular, the objective-surface distance was increased or decreased in d = 100 µm steps from the focal point (Zo). This procedure was performed for different laser power values.
Using the methodology outlined above, it was possible to find an upper limit for the power value of the laser that should be used to ensure that the laser–film interaction was not intense enough to completely ablate the film and reach the substrate. Subsequently, each line was analyzed in SEM-EDS (FESEM, ZEISS MERLIN Compact; manufacturer, Carl-Zeiss-Strasse, Oberkochen, Germany) to measure the width of the ablated line (see Figure 3b). The morphology and composition of each line were also verified and compared to a non-irradiated nearby region that served as a reference for the comparison of irradiated and non-irradiated regions.
The optimum parameters found during the tests were a laser power of 2.5 mW and a scanning speed of 50.0 mm/s. For a line width w ≈ 50 μm, the fluence was 0.15 J/cm2. The scanning speed was selected to ensure the homogeneity of the fabricated line. After the tests, the thin films with dimensions of 0.5 × 0.5 cm2 were irradiated and separated into two groups.
For the first group (Group I), only half of the surface area was irradiated—that is, 0.25 × 0.5 cm2. Using these samples, electrical transport measurements were performed to compare the irradiated and non-irradiated areas and directly evaluate the changes generated by the interaction between the ultra-short femtosecond laser beam and the film.
For the second group (Group II), the full film area was raster-irradiated for XRD characterization. It is important to note that films from groups I and II were produced simultaneously during a single PLD deposition to prevent any kind of changes in morphology or thickness.
Lines were drawn (irradiated) side by side, separated by approximately 1 μm, as indicated in Figure 3c, to cover the desired area of the film surface. During the laser raster scanning over the surface of the film, the distance between the lines was chosen to avoid any overlap between them. It is important to note that due to the low fluence used, changes in the surface of films were imperceptible to the naked eye.
The crystal structures of irradiated and non-irradiated LNO films grown on different substrates were characterized by XRD θ–2θ scans (XRD, Rigaku D/MAX-2500; manufacturer: Rigaku, Cedar Park, TX, USA) with a Cu K-α radiation source (λ = 1.5406 Å). Electrical transport was measured using the conventional four-point-probe method. For these measurements, metal electrodes (Ag, 100 nm with a diameter of 500 µm and also separated by 500 µm) were micro-fabricated using standard lithographic/masking techniques.
Four-point-probe transport measurements were performed from 8 to 300 K using a closed-cycle helium cryostat (Janis model CCS150; manufacturer, Lake Shore Cryotronics, Westerville, OH, USA). The samples were kept at a pressure lower than 5 × 10−6 mbar. The resistance was measured with standard low-frequency AC lock-in (Signal Recovery model 7265; manufacturer, AMETEK Advanced Measurement Technology, Oak Ridge, TN, USA) at f = 13 Hz and DC techniques (Keithley SMU model 2400C; manufacturer, Tektronix, Beaverton, OR, USA). The excitation current was adjusted to avoid nonlinear transport from high-field effects and undesired Joule heating. Initial electrical characterization (current-voltage curves) displayed a linear shape.

4. Conclusions

The electrical behavior of LaNiO3 thin films deposited on different substrates MgO, LaAlO3, and SrLaAlO4 (100) by PLD and subsequently irradiated with a femtosecond laser was investigated. Structural and morphological characterizations indicate that epitaxial thin films have been obtained with crystallographic orientation and good surface quality without surface outgrowths or particulates on the surface of the film.
From the XRD results, we observed a slight contraction in the lattice parameters of the growth direction and the (l00) planar distance for the irradiated samples. These contractions arose from the changes in the bond lengths and angles of [NiO6] clusters due to structural rearrangement by the Jahn–Teller effect, which directly affected the electrical behavior of the sample.
The temperature-dependent resistivity curves show a substantial decrease in resistivity when samples were irradiated with ultrashort pulses from a Ti: Sapphire. The reduction values ranged from 45% to 52% at a temperature of 10 K and 38% to 46% at 300 K. In all cases, resistivity decreased independently of the type of substrate used, i.e., regardless of the substrate and film mismatch (tensile or compressive strain). SEM-EDS results of irradiated regions suggested that the subtle difference in the La/Ni ratio, with a value close to 0.9, is related to the decrease in the resistivity of the LNO films due to the oxygen around Ni atoms. In brief, ultrashort pulses in air drive a highly non-equilibrium, non-thermal interaction with minimal heat-affected zone. Under these conditions, preferential cation removal (surface La depletion) and slight oxygen redistribution can occur at the near-surface, resulting in La/Ni < 1 in the irradiated tracks, as measured by SEM-EDS (La/Ni ≈ 0.9). The resulting [NiO6] octahedral distortions (shorter Ni–O, larger Ni–O–Ni angle) enhance bandwidth and lower resistivity, consistent with the literature on cation off-stoichiometry lowering ρ in LNO [26,27,28,29].
This new method for the in situ micrometric control of the electrical resistivity of LNO thin films can be prospectively employed to achieve specific changes in resistivity in micrometric regions of functional devices to fulfill the modern industrial miniaturization requirement. As mentioned in the introduction, our data, obtained using the PLD technique followed by femtosecond laser irradiation, showed greater reliability and a precise control of results when compared to other techniques such as molecular beam epitaxy and the sol–gel method. This indicates that the technique developed and presented in this work can provide better and more reliable samples for application in non-volatile-memory devices. Laser technologies allow for the micrometric control of irradiation and can be applied in a fine-tuned, fast, and permanent way, besides the reduction in the amount of energy used to make such modifications and so the energy costs. We have shown that it is possible to adjust the values of LNO electrical resistivity, thus highlighting the promising application of the manufactured LNO thin films as NVM devices. It is important to note that resistivity reduction values larger than 40% at room temperature, such as those achieved for the femtosecond-irradiated LNO thin films, represent a great advantage for the manufacture of miniaturized electronic devices in terms of energy efficiency and temperature management due to the reduced thermal-energy losses. Therefore, the results presented here use a new and innovative femtosecond laser irradiation route to decrease the electrical resistivity values in an in situ, precise, controlled, and localized manner, which could not be performed directly by well-known growth processes. These findings may pave the way for the development of highly technological integrated circuits for nanodevices and quantum computers.
The ability to locally and permanently reduce the electrical resistivity of LaNiO3 thin films through femtosecond laser irradiation opens new avenues for engineering the performance of functional oxide materials at the microscale. This technique enables the in situ tuning of transport properties without compromising the film crystallinity, offering a non-invasive, maskless, and scalable method for the post-fabrication optimization of oxide-based electronic components.
From a technological standpoint, this approach is particularly attractive for the development of non-volatile-memory (NVM) devices and other miniaturized systems where selective resistivity control is critical. The observed resistivity reductions—exceeding 40% at room temperature—translate into lower-Joule heating and improved energy efficiency, which are essential for the advancement of high-density, thermally stable integrated circuits and quantum electronic platforms. The methodology presented here may serve as a foundation for future device architectures requiring the precise control of electronic transport at micrometric or nanometric scales.

Author Contributions

Conceptualization: L.C.J., C.D.-B., M.T.F.-A., M.A., J.P.d.C.d.C., J.P.P.d.C., E.C.-C., H.B.M., O.H.A.J., J.M.A.B., A.J.C. and E.L.d.S., investigation and simulation L.C.J., C.D.-B., M.T.F.-A., M.A., J.P.d.C.d.C., J.P.P.d.C., E.C.-C., H.B.M., O.H.A.J., J.M.A.B., A.J.C. and E.L.d.S., writing and final editing: L.C.J., C.D.-B., M.T.F.-A., M.A., J.P.d.C.d.C., J.P.P.d.C., E.C.-C., H.B.M., O.H.A.J., J.M.A.B., A.J.C. and E.L.d.S. All authors have read and agreed to the published version of the manuscript.

Funding

This work was supported by the Grant CEPID/CDMF-São Paulo Research Foundation-FAPESP (grants numbers 2023/13792-4, 2022/10340-2, 2014/01371-5, 2017/23663-6, 2013/07296-2, 2019/18656-6), CNPq and CAPES. The authors also acknowledge the financial support from the Ministerio de Economia y Competitividad (CTQ2015-65207-P), Spanish Ministerio de Ciencia e Innovación (PID2020–116031RB-I00), Generalitat Valenciana (CIDEIG/2023/8 within Gen-T program), Xunta de Galicia/FEDER (project No. ED431B 2023/07) and the Agencia Estatal de Investigación, AEI (project No. PID2022-138322OB-I00). The O.H.A.J. was funded by the Brazilian National Council for Scientific and Technological Development (CNPq), grant numbers 407531/2018-1, 303293/2020-9, 405385/2022-6, 405350/2022-8 and 40666/2022-3.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author.

Acknowledgments

The authors would like to thank Gladys Mínguez-Vega from GROC–UJI for her support and valuable discussion about the employment of the femtosecond laser. The authors would also like to thank the Servei Central d’Instrumentació Científica of the Universitat Jaume I for the employment of the facilities and equipment. The authors acknowledge the support of the Coordination for the Improvement of Higher Education Personnel (CAPES) and the Brazilian Council for Scientific and Technological Development (CNPq) for financial support.

Conflicts of Interest

The authors declare no conflicts of interest.

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Inorganics 13 00297 g001
Figure 1. Panel (a) shows the experimental setup for the electrical measurements. In panels (b–d), the temperature dependence resistivity of LNO films grown on different substrates (LAO, MgO, and SLAO, respectively) are depicted. The green curves represent measurements in the non-irradiated regions, and the purple ones correspond to those performed in the irradiated regions. The approximate Δρ values at room temperature are also shown. In (e), an FEG-SEM image of an LNO/LAO film irradiated by the laser beam is shown. It can be seen that the thickness reduces from 100 nm in the non-irradiated region to 67 nm. Panel (f) shows a scheme for a better visualization and understanding of the image in panel (e).
Figure 1. Panel (a) shows the experimental setup for the electrical measurements. In panels (b–d), the temperature dependence resistivity of LNO films grown on different substrates (LAO, MgO, and SLAO, respectively) are depicted. The green curves represent measurements in the non-irradiated regions, and the purple ones correspond to those performed in the irradiated regions. The approximate Δρ values at room temperature are also shown. In (e), an FEG-SEM image of an LNO/LAO film irradiated by the laser beam is shown. It can be seen that the thickness reduces from 100 nm in the non-irradiated region to 67 nm. Panel (f) shows a scheme for a better visualization and understanding of the image in panel (e).
Inorganics 13 00297 g001
Inorganics 13 00297 g002
Figure 2. XRD patterns of LNO films grown on (a) LAO, (b) MgO, and (c) SLAO substrates. (d) (200) d-spacing. (e) A lattice parameter of non- and irradiated LNO films. (f) Pseudo-cubic unit cell of LaNiO3.
Figure 2. XRD patterns of LNO films grown on (a) LAO, (b) MgO, and (c) SLAO substrates. (d) (200) d-spacing. (e) A lattice parameter of non- and irradiated LNO films. (f) Pseudo-cubic unit cell of LaNiO3.
Inorganics 13 00297 g002
Inorganics 13 00297 g003
Figure 3. (a) Scheme showing the laser beam, objective, and positions relative to the focal point (Zo) separated by a d = 100 µm space where the tests were performed. (b) Lines irradiated at each of the different positions relative to the focal point. (c) Sketch representing the lines drawn (irradiated) by the femtosecond laser beam. (d) Indication of the irradiated and non-irradiated areas.
Figure 3. (a) Scheme showing the laser beam, objective, and positions relative to the focal point (Zo) separated by a d = 100 µm space where the tests were performed. (b) Lines irradiated at each of the different positions relative to the focal point. (c) Sketch representing the lines drawn (irradiated) by the femtosecond laser beam. (d) Indication of the irradiated and non-irradiated areas.
Inorganics 13 00297 g003
Table 1. The data presented in this table is taken from Figure 1b–d. The data sets are separated into two blocks. (i) Resistivity values for the non-irradiated (Normal) and irradiated (Irrad) regions at 10 K. (ii) Resistivity values for the non-irradiated (Normal) and irradiated (Irrad) regions at 300 K.
Table 1. The data presented in this table is taken from Figure 1b–d. The data sets are separated into two blocks. (i) Resistivity values for the non-irradiated (Normal) and irradiated (Irrad) regions at 10 K. (ii) Resistivity values for the non-irradiated (Normal) and irradiated (Irrad) regions at 300 K.
Substrate(i) ρ (T = 10 K) (μΩ·cm)(ii) ρ (T = 300 K) (μΩ·cm)
NormalIrrad.Decrement (%)NormalIrrad.Decrement (%)
LAO57.0331.1045.5150.1191.0339.4
MgO248.08152.5138.5535.51330.6638.3
SLAO4039.321940.8052.04451.102376.7946.6
Table 2. Parameters employed for PLD deposition. Thin-film deposition temperature (Tdep), oxygen pressure during deposition (Pdep), and distance between target and substrate (Dt−s).
Table 2. Parameters employed for PLD deposition. Thin-film deposition temperature (Tdep), oxygen pressure during deposition (Pdep), and distance between target and substrate (Dt−s).
Crystal SubstrateTdep (°C)Pdep (mbar)Laser Fluence (J/cm2)Dt−s (cm)
LAO6101.2 × 10−11.684.5
MgO6701.8 × 10−11.845
SLAO6451.8 × 10−11.654
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Cichetto Junior, L.; Doñate-Buendía, C.; Flores-Arias, M.T.; Aymerich, M.; Costa, J.P.d.C.d.; Cordoncillo-Cordoncillo, E.; Carmo, J.P.P.d.; Ando Junior, O.H.; Beltrán Mir, H.; Bort, J.M.A.; et al. Electrical Resistivity Control for Non-Volatile-Memory Electrodes Induced by Femtosecond Laser Irradiation of LaNiO3 Thin Films Produced by Pulsed Laser Deposition. Inorganics 2025, 13, 297. https://doi.org/10.3390/inorganics13090297

AMA Style

Cichetto Junior L, Doñate-Buendía C, Flores-Arias MT, Aymerich M, Costa JPdCd, Cordoncillo-Cordoncillo E, Carmo JPPd, Ando Junior OH, Beltrán Mir H, Bort JMA, et al. Electrical Resistivity Control for Non-Volatile-Memory Electrodes Induced by Femtosecond Laser Irradiation of LaNiO3 Thin Films Produced by Pulsed Laser Deposition. Inorganics. 2025; 13(9):297. https://doi.org/10.3390/inorganics13090297

Chicago/Turabian Style

Cichetto Junior, Leonélio, Carlos Doñate-Buendía, María Teresa Flores-Arias, Maria Aymerich, João Paulo de Campos da Costa, Eloísa Cordoncillo-Cordoncillo, João Paulo Pereira do Carmo, Oswaldo Hideo Ando Junior, Héctor Beltrán Mir, Juan Manuel Andrés Bort, and et al. 2025. "Electrical Resistivity Control for Non-Volatile-Memory Electrodes Induced by Femtosecond Laser Irradiation of LaNiO3 Thin Films Produced by Pulsed Laser Deposition" Inorganics 13, no. 9: 297. https://doi.org/10.3390/inorganics13090297

APA Style

Cichetto Junior, L., Doñate-Buendía, C., Flores-Arias, M. T., Aymerich, M., Costa, J. P. d. C. d., Cordoncillo-Cordoncillo, E., Carmo, J. P. P. d., Ando Junior, O. H., Beltrán Mir, H., Bort, J. M. A., da Silva, E. L., & Chiquito, A. J. (2025). Electrical Resistivity Control for Non-Volatile-Memory Electrodes Induced by Femtosecond Laser Irradiation of LaNiO3 Thin Films Produced by Pulsed Laser Deposition. Inorganics, 13(9), 297. https://doi.org/10.3390/inorganics13090297

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